68000

[ Die shot of Motorola 68000 [1] 68000 (MC68000, 68K),

a 16/32-bit CISC microprocessor designed and marketed by Freescale Semiconductor since 1979, started as a division of Motorola. It was used in Atari ST, Commodore Amiga, and Apple Macintosh personal computers, as well in Sun-1 workstations and many dedicated chess computers. 68000 has an external 16-bit data bus and 24 external address lines to index 16 MByte of physical memory, eight 32-bit general-purpose data registers (D0-D7), and eight address registers (A0-A7). The last address register was also the standard stack pointer, and could be called either A7 or SP [2]. Despite different data- and address registers, 68000 was known for its orthogonal instruction set [3]. Like its 8-bit predecessor 6800, but opposed to x86, 68000 is a Big-endian machine.